[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v4 4/9] xen: introduce XEN_DOMCTL_devour
Julien Grall <julien.grall@xxxxxxxxxx> writes: > Hi Vitaly, > > On 03/12/2014 17:16, Vitaly Kuznetsov wrote: >> New operation sets the 'recipient' domain which will recieve all > > s/recieve/receive/ > >> memory pages from a particular domain and kills the original domain. >> >> Signed-off-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx> >> --- >> @@ -1764,13 +1765,32 @@ void free_domheap_pages(struct page_info *pg, >> unsigned int order) > > [..] > >> + else >> + { >> + mfn = page_to_mfn(pg); >> + gmfn = mfn_to_gmfn(d, mfn); >> + >> + page_set_owner(pg, NULL); >> + if ( assign_pages(d->recipient, pg, order, 0) ) >> + /* assign_pages reports the error by itself */ >> + goto out; >> + >> + if ( guest_physmap_add_page(d->recipient, gmfn, mfn, order) ) > > On ARM, mfn_to_gmfn will always return the mfn. This would result to > add a 1:1 mapping in the recipient domain. > > But ... only DOM0 has its memory mapped 1:1. So this code may blow up > the P2M of the recipient domain. I know almost nothing about ARM so please bear with me. So, for a guest domain the mapping is not 1:1 (so guest sees different addresses) but mfn_to_gmfn() doesn't returs these addresses? I was under an impression it is not x86-specific and I can see its usage in e.g. getdomaininfo(), memory_exchange(),.. How can one figure out the mapping then? Anyway, what I want to do here is: when this page is freed I want to reassign it to our newly-created guest at the exact same address it was mapped in the original domain. > > I'm not an x86 expert, but this may also happen when the recipient > domain is using translated page mode (i.e HVM/PVHM). PVHVM is the main target here (as kexec is unsupported for PV) and it kinda works. mfn_to_gmfn() returns gmfn != mfn. BTW, what's the current state of affairs with kexec and ARM guest? I suppose we should have similar problems: vcpu_info, event channels, .. > > Regards, -- Vitaly _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
|
Lists.xenproject.org is hosted with RackSpace, monitoring our |